It's an interesting thesis in that it rests on the idea that Cameron could lose a general election which the Tories were once expected to win comfortably yet still survive as party leader.
But is he right? Well, history - particularly that of the Tory Party - would strongly suggest otherwise.
The last party leader to be given a second chance after losing one election was Neil Kinnock (1987 and 1992), but he was leader of the Labour Party which traditionally has a more tolerant attitude to defeat. The only post-war Tory leader to be given two bites at the cherry was Edward Heath (1966 and 1970), and this may have been influenced by the fact that he had only been in the job a year when the first of those contests took place.
There is a common consensus that had she lost the 1979 election, even Margaret Thatcher would have been swiftly despatched in favour of a more traditonal, reassuring figure like Jim Prior or Francis Pym.
So could Cameron really buck this trend? Well, I suppose it depends partly on the alternatives.
Some on the right still hanker after a David Davis leadership, but he will be in his 60s by the time the election after next comes round. Liam Fox is the likeliest right-wing challenger, but he has always seemed to me to lack ruthlessness.
Meanwhile William Hague has said repeatedly he does not want the job, certainly not while the party is still in opposition. Chris Grayling is the dark horse, but he scarcely rivals Cameron in the charisma stakes.
It will also, of course, depend on the closeness of the result. If Cameron can succeed in turning Gordon Brown into a John Major figure, dependent on a wafer-thin majority and ever-fighting to beat back the tide of the inevitable Tory advance, then I guess he may well continue in the job.
But even then, I don't expect it will be without a fight.